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Setting a static IP address in Ubuntu

Submitted by admin, on January 18th, 2012

During a default install of Ubuntu it will try and automatically obtain an IP address using DHCP. While that may be fine for most users, if you are wanting to set up a server, the chances are you will be wanting it to always have the same IP address.

There are two options for ensuring you get/use the same IP address at every boot. You could set up a IP address reservation on the DHCP server based on the hardware/mac address of the network interface, or alternativly, set the operating system to use a static IP address. If for whatever reason you dont want to go down the path of setting a DHCP reservation (you may not have access to the DHCP server; unsure how to set it up; etc), the only option is to set a static IP address on the PC itself.

The following steps will guide you through setting up your computer to use a static IP address on Ubuntu.

Open up the /etc/network/interfaces file in your favorite editor. This guide will be using the “nano” editor.

sudo nano /etc/network/interfaces

You should see the lines similar to the following in the editor.

# The primary network interface
auto eth0
iface eth0 inet dhcp

The line containing “iface eth0 inet dhcp” needs to either be deleted, or commented out. I choose to comment it out, and add the configuration lines to set up a static IP directly below it. This allows you to change it back easily at a later date if you want to. The # character at the beginning of the line indicates that it is commented out, and will be ignored.

Add the following lines to set up the interface with a static IP. Make sure you change the relevant settings to suit your network.

If you are unsure what settings should go in this file, you can always run the ‘ifconfig’ command, which will output the current IP address settings obtained via DHCP. The default gateway address can be obtained by using the ‘route’ command.

Once you have finished with the changes to the file, save and quit the editor.

You will also need to set up the DNS nameserver settings manually. These are stored in the /etc/resolv.conf file.

Open this file in your editor.

sudo nano /etc/resolv.conf

you will want at least 1 nameserver set up in this file. If one already exists, and is valid, great. If not, add one or more nameserver records in the format below.

nameserver 192.168.0.1

Depending on your setup, this could be your router’s IP, your ISP’s DNS server IP, or a 3rd party’s DNS server, such as Google’s (8.8.8.8 and 8.8.4.4), or OpenDNS.

Save and exit the editor.

To activate the changes you will need to reboot the PC, or simply restart networking (recommended).